I study experimental evolution by using microorganisms, particularly bacteriophage, as a model system. Currently my research focuses on two areas: (1) the genetic basis for the evolution of life history traits, with phage lambda as a model system, and (2) the identification of bacterial enzymes targeted by ssRNA phage lysis proteins. Based on the detailed molecular information we have on the simplest organism in a most simplified environment, we can make specific predictions on the evolutionary pathways and trade-offs among various traits important to phage fitness. Competition experiments and long-term evolution experiments are used to test the validity of these predictions. Related questions include the evolution of genome size and the attainability of co-adapted genome under rampant recominational flux of large scale genome exchanges. It has been shown that ssDNA and ssRNA phage lyse their hosts by producing a single lysis protein that works as an inhibitor for enzymes involved in cell wall synthesis. By identifying various enzymatic steps targeted by these bacteriophages, it is hoped that we can uncover an alternative, and potentially useful, resource for making new generations of antibiotics.